A common industrial process for producing an amide compound involves Beckmann rearrangement of a corresponding oxime compound. For example, ε-caprolactam which is industrially useful is produced by Beckmann rearrangement of cyclohexanone oxime. A rearrangement catalyst is generally concentrated sulfuric acid and oleum, and since these strong acids must be used in the stoichiometric amounts or more, a large amount of ammonium sulfate are formed as a byproduct during neutralization.
There is, therefore, a need for a Beckmann rearrangement catalyst with least environmental impact.
As for producing processes for laurolactam, Patent Reference Nos. 1 and 2 have disclosed that laurolactam is produced by Beckmann rearrangement of cyclododecanone oxime or its hydrochloride using a catalytic amount of, for example, phosphorous trichloride, phosphorous pentachloride, thionyl chloride and sulfuryl chloride. However, in this method, selectivity is inadequate, a reaction product is strongly colored, and product quality is unsatisfactory.